Re: [PATCH v2 01/10] technical doc: add a design doc for the evolve command

[Victoria Dye <vdye@github.com>]

Phillip Wood wrote:
> On 10/10/2022 20:35, Victoria Dye wrote:
>> Stefan Xenos via GitGitGadget wrote:
>> 3. Can't handle multiple changes sharing the same parent when the parent
>>     needs to be rebased
>>     - Since the introduction of '--update-refs' [1], this is technically
>>       possible (although it needs a UI for the use case you mentioned).
> 
> '--update-refs' is more limited though I think. With evolve if I have
> 
>                   D (topic-2)
>                  /
>     A - B - C (topic-1)
>                  \
>                   E (topic-3)
> 
> then if I checkout topic-1 and amend one of the commits I can run "git
> evolve" to automatically rebase topic-2 & topic-3. One cannot do that with
> "rebase --update-refs". We could extend rebase (or have a new command) so
> that users can say "amend commit X and rebase all the branches that contain
> it".

Sorry, let me clarify what I mean. The 'update-ref' command in a
'rebase-todo' script (not the '--update-refs' option) can be used to create
a rebase script that does what's described in your example:

  label onto # A

  reset onto
  pick 1342ab B
  fixup 8a7f3e fixup! B
  label branch-point-1

  pick 90d7fc C
  label topic-1
  update-ref refs/heads/topic-1

  reset branch-point-1
  pick 42f92b D
  label topic-2
  update-ref refs/heads/topic-2

  reset branch-point-1
  pick 06d8ec E
  label topic-3
  update-ref refs/heads/topic-3

So, while it'd need a less manual UI (e.g., a 'rebase --evolve' option) to
generate that script, the 'update-ref' command makes this functionality
possible in a rebase.